On a general note, I cannot determine which window is frontmost in several of the screenshots – the window titlebar or toolbar icon coloring/lighting do not change depending on layering or focus. I believe this is the case with Keramik (at least with the titlebars), so the Plastik theme may be a step backwards in usability.

Several of the icons in the left-hand pane of Kontact could be improved by stripping them down to their essential elements:

The e-mail icon (which is simply K-Mail’s default icon) could be improved by removing the E altogether and showing an envelope with a large postage stamp on it. The angular perspectives of the E and the envelope decrease the recognizability of these two elements.

The Phone for Contacts is decent, but contacts are organized around people or organizations. An icon showing individual “people” would be better.

A better icon for the Todo List would be just several checkboxes on a single piece of paper. In the current icon, the main elements are the book and the pencil – the checkboxes are ghosted and very small.

The calendar icon should be reduced to a single month calendar sheet as found in traditional paper calendars or something like a single day sheet from a single day tear-off calendar.

Overall, the icons in the Kontact pane do not look as though they belong together – they do not share elements such as coloring and perspective. I know this is because the applications that make up Kontact were developed separately, with each one using slightly different icon styling. Just look at the difference between the Calendar and Todo List icons – Calendar is done in the Crystal style with an angled visual perspective while Todo List looks very KDE 2.0 with its head-on perspective. The Notes icon uses a photo-realistic style that doesn’t go with any of the other icons.